Method of regulating multicircuit-generators.



No. mass.V Patented nec. le, 1902.

l H. H. wm. METHOD DF HEGULATING MULTIGIRCUIT GENERTOBS.

(Application 'med my 5, 1902.)

(No Model.)

776' l C v@ze me Nomus persas o o., PHaToLlmo.. wnsnwmon, I5. c.

UNITED STATES PATENT OFFICE.

HENRY I-I. IVAIT, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRICCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

METHOD OF REGULATING MULTlClRCUlT-GENERATORS.

SPECIFICATION forming part of Letters Patent No. 716,355, dated December16, 1902. Application filed May 5, 1902. Serial No. 105,939. (No model.)

To all whom it may concern.:

Be it known that I, HENRY H. WAIT, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois,

have invented a certain new and useful Improvement in Methods ofRegulating Multicircuit-Generators, (Case No. 17,) of which thefollowing is a full, clear, concise, and exact description.

to My invention relates to a method of regulating electric generators ofthe multicircuit type-that is, where two or more working circuits, suchas series arc -lamp circuits, are supplied from dierent sets of brusheswhich l5 take current from a single armature. It will be seen that in anarc-machine where the armature necessarily has a very high reaction amovement of the brushes supplying one circuit to compensate for a changeof load in that circuit will change the circumferential distance on thecommutator between these brushes and the'brushes belonging to the othercircuit, so that if constant current is maintained the armature reactionwill be va- 2 5 ried, causing a variation in the intensity anddistribution of the magnetic flux threading the coils undergoingcommutation. The result will be that this change in the reversingieldacting on the coils undergoing commutation will cause a variation in thecurrent flowing through these short-circuited coils, such thatseriousand destructive sparking may be produced.

My invention has for its object more particularly to prevent such'sparking as the brushes of one circuit are shifted to compensate forchange of load; and it consists, briefly, in maintaining the currents inthe coils undergoing commutation at their proper predetermined values byvarying the components which go to produce such currentsthat is, byvarying the ampere-turns on the iield-poles or varying the number ofturns of the armature-winding which are short-circuited by the brushesinproportion to the changes caused by the unequal distribution of thearmature reaction. The preferred method of doing this is to 4vary thespan of each brush to increase or diminish the number of turns of thearmature-winding shortcircuited thereby in inverse ratio to the changein magnetic flux threading the shortcircuited coils as the brushes ofone circuit or the other are shifted.

I will describe my invention by reference to the accompanying drawings,in which-- Figure l is a diagram illustrating a multipolar generatorwith two pairs of brushes, each pair supplying an individual circuit,the machine being constructed so that the span 6o of each of the fourbrushes will be varied when either pair of brushes is shiftedindependently ofthe other pair to compensate for change of load on thecorresponding circuit. Fig.` 2 is a similar diagram illustrating 65 amodification of my invention,in which the current in the coilsundergoing commutation is maintained practically constant under changesof armature reaction by varying the ampere-turns on the field tocompensate for 7o such changes instead of by varying the other componentgoing to produce such commutation-current-that is, the number of turnsof armature-winding which are short-circuited by the brushes. The samecharacters of reference are used to designate the same parts in bothgures.

Referring first to Fig. 1, the armature a is arranged to rotate withinthe influence of the field-magnet h, which is provided with four 8opoles b b2 b3 b4. Two pairs of brushes are provided for taking thecurrent from said armature, said pairsof brushes being carried by theindependently-movable rocker-arms c c2. The rocker-arm c', which carriesthe 85 pair of brushes cl e, is arranged to be swung about its axis bythe regulating device R to shift the position of the brushes as the loadon the circuit l, supplied from said brushes,

is varied, the regulating device R' being me- 9o chanically connectedwith the rocker-arm c' by the link f'. Similarly the rocker-arm c2 isconnected by a link f2 with the regulating device R2, whereby the otherpair of brushes g h, supplying the other circuit 2, is shifted inaccordance with the change of load on the latter circuit. Suchregulating devices are well known in the art and need no particulardescription. Each brush consists of a stationary member fixed uponl anarm of the Ioo rocker and a movable member'carr'ied by a lever k',pivoted so that the movable member of the brush may be moved closer toor farther from the stationary member thereof by rocking said lever 7cabout its pivot, whereby the span ofthe brush may be adjusted toincrease or decrease the number of turns of the armature-windingrshort-circuited thereby. The levers lt 7s of each rocker are connectedby links Z Z with the other rocker, so that when either rocker is movedindependently of the other the several arms 7c will be moved about theirpivots to change the span of the brushes. The levers and links arepivoted and arranged so that when either rocker-arm is shifted in adirection to bring the brushes d and g or the brushes e and h toward oneanother the span of each of the two brushes which approach each otherwill be decreased, while the span of each of the other brushes will beincreased. The operation of this machine is as follows: The rockers c@zare both shown in the positions they would occupy with full load onboth the circuits l 2. Assume now that the load on the circuit 2 isdecreased, as by cutting outsome ofthe arc-lamps which are connected inseries in such circuit. The regulator R2 will immediately act tomaintain the current constant byshifting the rocker-arm c2 to move thebrushes g and h from the position shown to positions nearer the centerof the pole pieces b4 and bo, respectively. The brushes d and g willthus be brought nearer together, while the brushes e and h will beseparated, the result being that the number of turns on the armaturebetween brushes CZ and g is decreased, while the number of turns betweenthe brushes e and h is increased. The reactive ampere-turns on thearmature between brushes CZ and g-that is, between pole-pieces ZJ' andbig-being thus diminished a change in the distribution of the eldmagnetism will result, the magnetic iiuX from pole-pieces b' and b3being considerably increased. Brushes e and t being moved apart themagnetic flux from polepiecesbQandZ24isdecreased. Sparkingwould nowresult owing to the change in the re- Versing-fields at the severalbrushes-that is, the change in the magnetic forces which go to build upcurrents in the coils undergoing commutation. In accordance with myinvention, however, the currents in the coils undergoing commutation aremaintained at their proper predetermined values by varying the netmagnetizing force acting on said coils to compensate for the unequaldistribution of the armature reaction, and in the arrangement of Fig. lthis `is done by varying the number of turns of armature-winding whichare short-circuited by the brushes-- that is, by varying the number ofturns which generate the electromotive force required to build up thecommutation current in the short-circuited coils. The magnetic iiuX frompole-pieces band b3 being increased the movable members of the brushesCZ and g are moved toward the stationary members of said brushes bythelcver mechanism as the rockerarm c2 is shifted to the left, so that aless number -of the armature -coils is short-circuited by the brushes dand gto compensate for the increase in the magnetic flux which threadsthe coils undergoing commutation at said brushes, so that the currentsbuilt up in the short-circuited coils are maintained at their properpredetermined values. Similarly when either of the two brushes d and gore and 7i are separated, as would be the case with brushes e and 7Lwhen the rockerarmo2 is moved toward the no-load position, the levermechanism will act to bring the movable members of said brushes awayfrom the iiXed members thereof, thus increasing the span ofthe brushesto compensate for the decrease in magnetism threading the coils spannedthereby.

Referring now to Fig. 2, no means are shown for varying the span ofthebrushes; but in place thereof switches m m are provided forshort-circuiting portions ofthe winding on the several held-magnetpoles, these switches being controlled jointly by the two rockerarms cc2, which carry the two sets of brushes.

Each field-magnet has associated therewith a switch consisting of astrip of contacts connected with different points on the fieldwinding,and two brushes m m2, which are electrically connected together, arearranged to slide along each strip of contact-pieces. The number ofampere-turns on any fieldpole may thus be changed by moving the twobrushes of its switch toward or away from one another to vary theportion of the fieldmagnet short-circuited by said brushes. The brushesm m2 of each switch are connected by links with the rocker-arms c c2,respectively, so that as either rocker-arm is moved it will change thepositions of the brushes m m2 of all the switches. W'hen the movement ofthe rocker-arms is in a direction to bring the collecting-brushes dand gnearer together, it will be seen that the decrease in the armaturereaction between these brushes will be compensated for by the separationof the two brushes m m2 of the switches which control the field-magnetsb and b3, respectively, thus decreasing the ampere-turns on these twopoles. Similarlya movement of the rockerarms to bring brushes e and hnearer together will result in weakening the field strength of poles b2and b4. A movement of either of the two brushes d and g ore and h awayfrom each other will bring about a strengthening of the correspondingheld-poles to compensate for the increase in armature reaction betweenthem.

I do not wish to limit my invention to the exact form ofmulticircuit-machine shown in the drawings, but wish to include any formof generator in which two or more individual circuits are supplied fromdifferent sets of brushes on the same armature.

In another application, Serial No. 105,940, filed May 5, 1902, I havedescribed and claimed a regulating mechanism for varying the span IOOIIO

sparking, which consists in varying the number of turns of thearmature-Winding which are short-circuited in commutation, according tothe increase or decrease of the magnetic flux threading such portions ofthe armature caused by the change of armature reaction which resultsfrom shifting the brushes of one circuit independent of the other tocompensate for change of load.

In witness whereof I hereunto subscribe my name this 2d day of May, A.D. 1902.

HENRY H. WAI'I.

Witnesses:

DE WITT C. TANNER, W. W. LEACH.

